Removing black carbon may lead to warming

The international debate on Black Carbon (BC), believed to be a potent greenhouse gas, may see a fresh twist. An Indian scientist who is part of the core group in India's Black Carbon Research Initiative has said that removing black carbon may be counter-productive and lead to more warming.

BC has been a controversial topic in the international climate debate. While many Western nations have pushed for BC's inclusion in the list of greenhouse gases under the United Nations' Framework Convention on Climate Change, India has staunchly said no.

During the Cancun talks in December last year, former Environment Minister Jairam Ramesh had even declared: "We will resist any attempt to bring black carbon within the ambit of UNFCCC negotiations."

The scientist—Associate Professor S K Satheesh of the Centre for Atmospheric and Oceanic Sciences & Divecha Centre for Climate Change, IISc, Bangalore—said the removal of BC would mean the removal of other kinds of carbon (sulphate and organic) that act as coolants. This would thereby become more harmful for global warming's cause, he said.

"Both sulphate and organic carbon are the scattering type, and they are cooling agents. So if you are removing a BC source, you reduce one unit of BC, but also 10 units of scattering aerosol. Then, in effect you are actually warming. Unless we have a technology to only remove the BC, not the others," Satheesh told The Sunday Express . Satheesh is one of six scientists that formulated India's Black Carbon Research Initiative as part of the National Carbonaceous Aerosols Programme (NCAP), launched by the MoEF a few months after Cancun. The initiative is headed by his senior colleague, Professor J Srinivasan.

Satheesh added that the very nature of carbon aerosols is important: "BC is 23 per cent absorbing and 77 per cent scattering, while organic carbons are 97 per cent scattering and 3 per cent absorbing," he said, adding that the combined scattering is much larger than the combined absorption, thereby having cooling effects.

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